Our experiment is a study of quantum bits ("qubits") which perform the same function in a quantum computer as bits in a classical computer. For purposes of explaining this paper, never mind the details of what qubits are or how they work. The important thing is that to perform operations on a qubit we irradiate it to microwaves, but for this to work the qubit has to be tuned to the frequency of radiation we're using. We also use a SQUID (superconducting quantum interference device, a magnetic field detector) to detect the magnetic field from the qubit, but this device needs to be tuned as well to be sensitive to the qubit state. We accomplish both tunings by applying magnetic fields, and the easiest way to produce magnetic fields is by generating electric currents. The paper describes a circuit we built to generate these currents for tuning the device, which had to be very accurate, very stable, and computer controlled; it's more of an engineering result than a scientific one. Much of the abstract consists of various specifications of the circuit's stability.